1. Field of the Invention
The present invention relates to a display information exchange device for an electrostatic display apparatus, and more particularly to a device for partially exchanging the display information of a display apparatus constituted with many electrostatic display units arranged so as to form a matrix.
2. Prior Art
In the first place the principle of an electrostatic display unit. The unit is described is basically constituted with a fixed electrode, a movable electrode and an insulating layer, which is to prevent both the electrodes from being short-circuited when, as will be mentioned below, the moving electrode gets in touch with the fixed electrode. With a high voltage supplied between both of the electrodes, a produced electrostatic force pulls and bends the movable electrode so as to cover the fixed electrode. Thus the display unit has its appearance changed by an electrostatic force.
An example of such an electrostatic display units is shown in FIG. 1. In the figure a cylindrical inner fixed electrode 2 is mounted on a base 1. On both sides of the base 1 are fixed two film holders 3, 3 by which two film-like movable electrodes 4, 4 are held extending upward with their upper portions made to form free ends 5, 5. On the outer sides of the film holders 3, 3 two outer fixed electrodes 7, 7 are mounted with spacers 6, 6 inserted. The outer fixed electrodes 7, 7 have their middle portions hemi-cylindrically extruded inward. The base 1, the film holders 3, 3, lower portions of the movable electrodes 4, 4, the spacers 6, 6 and lower portions of the outer electrodes 7, 7 are totally fixed with screw bolts 8, 8. The outer surface of the inner fixed electrode 2 and the inner surfaces of the outer fixed electrodes 7, 7 are coated with insulating paints having their respective particular colors. On the other hand the both surfaces of the movable electrodes 4, 4 are mirror-finished. Further, the inner fixed electrode 2, the filmer holders 3, 3 and the outer fixed electrodes 7, 7 have their lowermost ends fabricated so as to provide their respective terminals 2A, 4A and 7A.
In the above constitution of the display unit, if a voltage is supplied between the terminals 4A and 7A, the movable electrodes 4, 4 open outward to fully dispose the inner fixed electrode 2. Therefor, the appearance of the display unit seen from above looks in the color applied to the inner fixed electrode 2. With a voltage supplied between the terminals 4A and 2A, the movable electrodes 4, 4 are bent so as to cover the surface of the inner fixed electrode 2, and therefore the seeming color of the display unit changes to that applied to the inner surfaces of the outer fixed electrodes 7, 7.
With many such electrostatic display units arranged in the length and breadth so as to form a matrix, an electrostatic display apparatus can be constituted. FIG. 2 shows an example of the pattern dot-displayed on such a display apparatus. The display apparatus can be made to display not only a static pattern but also a moving or a flowing patterns by shifting the display information at a constant speed or varying the display information gradually.
In some cases, however, it is desired to delete some of the provided pieces of display information or to replace them with other kinds of display information.